Singeing apparatus



April 11, 1961 F. J. CLENDENING, JR 2,978,783

FRANCIS J. CLENDEN|NG,JR.

April 11, 1961 CLENDENlNG, JR 2,978,783

SINGEING APPARATUS Filed July 31, 1957 2 Sheets-Sheet 2 FURNACE BOUNDARYINVENTOR FRANCIS J. CLENDENING,JR.

BY Q A 61% ATTORNEY United States Patent" 2,978,783 SINGEING APPARATUSFrancis J. Clendening, Jr., Wilmington, Del., assignor to E. I. du Pontde Nemours and Company, Wilmington,

DeL, a corporation of Delaware Filed July 31, 1951, Ser. No. 675,411 2Claims. (cl. 26-6) This invention relates to an apparatus for singeingfabrics and more particularly to an improved process for singeingfabrics constructed of synthetic fibers.

Various singers have been employed in the past chiefly for the finishingof cotton fabrics. Most of these singers possess certain shortcomings,particularly with respect to the maintenance of uniform temperaturesacross the surface of the fabric. With the advent of synthetic fiberfabrics, the difiiculties in singeing have multiplied. Not only is itnecessary to achieveuniform temperatures acrossthe surface of thesynthetic fabric, but more importantly, provision must be made toprevent build-up of molten polymer and the formation of molten polymerballs on the fabric surface.

, It is an object of this invention to provide a process for finishingfabrics, and particularly fabrics of synthetic fibers having highpilling propensity. Another object is to provide an apparatus forsingeing the surface of synthetic fabrics uniformly without allowingbuild-up of molten polymer balls. Other objects will be apparent from amore detailed description of the invention given below. i The aboveobjects are accomplished by providing a novel apparatus for finishingfabrics comprising in combination, a hollow metal roll the lower portionof which is suspended in a heating chamber and friction driven by adriving means inside said heating chamber, said driving means in turnbeing cradled on bearings which are outside said heating chamber, saidchamber having heating means preferably only in the sidewalls parallelto and facing said roll and an air gap separating the roll from thechamber at the sides, ends and bottom of the chamber and means forpassing fabric counter to direction of roll travel in instantaneouswiping contact with the top surface of said roll. The invention alsoincludes a process for finishing fabrics comprising conveying a fabricin instantaneous wiping contact with the top surface of a uniformlyheated hollow metal roll rotating counter to the passage of said fabric,and adjusting the speed of said fabric with the temperature of the rollsurface and the contact angle of fabric with roll such that only surfacefibers of the fabric are removed by thermal shock treatment withoutdestroying the fibers in the body of said fabric.

The invention may be more readily understood by reference to Figures 1and 2 which are plan views and illustrate, respectively, a suitablearrangement for singeing a fabric in contact with a rotating heatedroll, and a detailed view of a mechanism for supporting and rotating theheated roll to achieve maximum temperature uniformity.

Figure 1 shows a fabric 1 passing over tension bars 2 where the desiredamount of tension is applied. From here, it passes over a spreader roll3 and on to the steel hot roll 4. The amount of contact angle on the hotroll is determined by the position of idler roll 5, which is adjustable,in the vertical direction. Roll 5 is also used to facilitate string-upin starting the device in that it is mounted on an air operated, leverarm and may be readily retracted so the fabric is not in contact withthe heated roll. Driven nip rolls 6 control the speed of the fabricthrough the machine. The furnace 7 supplies a uniform gas flame whichburns in the area indicated as 8 to heat the roll which is mounted inthe furnace opening. This is produced by burning the gas at the twoinner side wall surfaces of the porous ceramic furnace lining 9, throughwhich it is fed from a manifold not shown.

Figure 2 shows the unique combination of elements for supporting androtating the hot roll to get maximum temperature uniformity. Hot roll 4is cradled by two heat-resistant stainless-steel rolls 10. These rollsare in turn cradled outside each end of the furnace between a bearingmounted disc 11 and two backup bearings 12. The roll shafts are extendedon one end and have attached gears 13. Separately mounted gear 14contacts gears 13 to rotate the idlers 10 and hence hot roll 4. Directlyconnected to gear 14 is sprocket 15, which transmits the power .torotate the system by means of chain 16.

One of the advantages of the present invention resides in thearrangement of the apparatus whereby the direct wiping contact of fabricwith the surface of the roll and the speed of the fabric over the hotroll in opposite directions allows any polymer which builds up on theroll as a result of finishing synthetic fabrics to be burned offcompletely during the singeing process. Another advantage is that thepresent arrangement of the apparatus permits the singeing of fabrics atspeeds far in excess of those commonly used heretofore. These superiorspeeds decrease the possibility of dye sublimation when singeing dyedfabrics. Another advantage is based on the fact that the thermal shockwhich the fabric undergoes in contact with the hot roll promotesretraction or pigtailing of loose fibers back'into the interstices ofthe fabric.

The superior temperature uniformity of the heated roll achieved in thepresent invention is attained in part by restricting heat losses throughline contact on rolling bearing surfaces. This eliminates heat lossthrough conventional shafting and water-cooled bearings. The uniformtemperature achieved is aided by using a hollow stainless steel tube andby avoiding spider mandrels. The usual corrugating and rippling effectsso often produced with open-flame singers are eliminated in the presentinvention by having the fabric directly contact the hot roll. Foroptimum results the fabric should. contact the exposed top surface ofthe heated metal roll over an arc of at least 10, the larger the arc themore uniform is the control of the singeing and generally the higher thequality of the singed fabric. The contact are may be varied inconjunction with the surface temperature of the hot roll and the speedof the fabric upon the roll depending on the particular fabric beingfinished. A particularly suitable are for singeing synthetic fabricsusing the preferred gas fired porous ceramic Walled heating meansillustrated in Figure 1 lies in the range of l5-20. All temperaturesreported herein for the hot roll are those measured with a thermocoupleat the top outer surface of the roll. It has been found that the rolltemperature must be adjusted with the fabric speed andthe compositionand construction of the fabric to obtain optimum singeing results. Thus,for example, :a woven fabric of polyethylene terephthalate blended witheither cotton or wool in proportions of 65/35 may be singedsatisfactorily on a roll at 1200" F. at the surface, whereas apolytheylene terephthalate woven fabric of the same construction shouldbe singed at 600-700 F. roll temperature to prevent destruction of thefabric. This difference is believed to be due to a different moisturecontent held by the two fabrics. Fabrics of 100% poly hexamethyleneadipamide may be singed at roll temperatures of 800 F.l200 F. Cotton andwool fabrics are generally singed at 800 F. to 1400 F. The temperaturerequirements of the'roll surface are such that the syn thetic fiber endsand fuzz protruding from the fabric be wiped off onto the rollsur'face'a'nd as the roll rotates past the side walls of the heatingchamber the temperature be high enough to be above the melting point ofany synthetic polymer fibers so as to cause the molten polymeraccumulation on the rollto' melt and drop off completely to the bottomof the chamber, leaving the roll surface completely free of polymer whenit again rotates into the top position ready to contact a new area ofmoving fabric. Any fibers composed of non-melting polymers or thenatural fibers will contact the roll at a temperature high enough tocarbonize the fiber ends and fuzz so that small pieces of the carbonizedfibers drop off the roll into the chamber almost as fast as the fabriccontacts the hot roll surface. The maximum temperature differentialmeasured across the length of the hot roll in Figure 1 when the topsurface is at 1200 F. is only 40 F., and this amounts to a substantialimprovement in temperature uniformity compared with prior methods andapparatus available for singeing fabrics. When using water-cooledbearings the differential across the top of the roll at the sametemperature of 1200 F. reaches 200-300 F. which leads to muchgreatervariations in the hand and aesthetics of the singed fabrics treated onsuch an apparatus.

The speed of the hot roll is advantageously run at about 5-25revolutions per minute, whereas most fabrics may be run in contact withthe roll at 100-300 yards/ minute for the particular temperatures andfabrics discussed above. The hollow metal hot roll may be constructed ofstainless steel tubing or any other type of steel, alloy steel, or iron,provided it will withstand the heating and reheating to statedtemperatures and maintain its smooth surface at these temperatures forlong periods of time. The two driving rolls (idlers in Figure 2 shouldbe made preferably of some heat resistant alloy steel (such as type309-C chromium-nickel steel) in order to withstand even hottertemperatures than the hot singeing roll and because these rolls expandupwards of two inches in length during firing of the singeing roll up totemperatures of about 1200" F.

In addition to the porous ceramic gas fired heating chamber illustratedin Figure 1, which is available commercially from Holden MetallurgicalProducts Company, other heating means may be used provided that theheating source directed toward the hollow singeing roll is not appliedin the form of jets and is not concentrated or applied to confinedareas. The heating source must be applied to raise and maintain thetemperature of the hollow singeing roll uniformly. Other useful heatingmeans include a cyclone fired furnace or an impingement type furnace.

The temperature uniformity obtained across the face of the fabric in theoperation of the present invention is realized by having the fabric indirect fiush supported contact with the hot moving smooth surface of thehot roll, which keeps the fabric flattened during singeing and while atmaximum temperature, compared with known open-flame singers which firethe fabric in unsupported condition and produce rippling, and knownstationary hot surfaces which cause the fabric to be overheated in someareas and unsinged in others.

The present invention may be used for singeing any type fabric composedof either natural or synthetic fibers or blends of the two. Examples ofsuch fabrics include those made from cotton, wool, rayon, celluloseacetate, polyamides, polyethylene terephthalate, acrylonitrile polymersand copolymers, vinyl chloride and vinylidene chloride polymers andcopolymers, and the like. The fabric may be dyed or undyed beforesingeing. The present invention may be applied to fabrics having a widevariety of constructions, such as shitting goods, dress goods, suitingfabrics, work clothes, and the like, particularly staple fabrics andthose having a tendency to form pills and fuzz.

The following examples are not limitative but illustrate specificembodiments of this invention. All parts are by weight unless otherwisespecified. The data given in the examples for pill counts was determinedon standard fabric test swatches which were subjected tot a pilling testfor 60 minutes in the random tumble pilling tester, as described byBaird, Legere and Stanley, Textile Research Journal, 26, 731 (September1956).

Example I A batiste shirting fabric of 65/ 35 polyethyleneterephthalate/cotton spun yarns was singed on the hot roll singer ofFigures 1 and 2 with the hot roll surface at 1200 F. and a fabric speedof 200 y.p.m., and then compared with commercially finished'goods,singed at y.p.m. with an open-flame singer. Data obtained from the testare as follows:

Hot Roll Commer- Singed clally Singed P111 nmmi' 1 2 1,4; Melt ballcount (per sq. in. of fabric above 400 2,400. surface). Aesthetics(Subjective) Very smooth-.. Smooth Example I] A madras shirting fabricwoven of 100% polyeaproamide spun yarns was run on the same hot-rollsinger at 1200 F. with remarkable aesthetic improvement over open-flamesinged samples. The vastimprovement was attributed to the dramaticreduction of the usual attendant surface melt balls.

Example 111 On Oxford shirting fabric of 65/35 polyethyleneterephthalate/ cotton spun yarns was singed on the same hot roll at 1200F. at 250 yards per minute fabric speed and compared to the commerciallyfinished goods, singed at 75-100 yards per minute on a conventionalopenfiame singer. Data obtained from the test are as fol- Example IV Abatiste fabric of 60/40 polyethylene terephtha late/cotton spun yarnswas dyed with a dye formula designed to emphasize sublimation. Thisfabric was singed on the same hot roll as in Example I. A wetparison ofuniformity from selvedge to selvedge and end to end revealed nosublimation of dye or other shade change as a result of the singeingprocedure.

Example V Swatches of the same fabric from Example IV were pill testedand results of the hot-roll samples end to end and selvedge to selvedgeshowed perfect uniformity of 1.0 pill rating. Swatches of the samefabric singed on a standard open-flame commercial singer gave variableratings of 1.5 to 2.0 pills.- r

The present invention offers many advantages over the prior art. It hasbeen found that fabrics which have a. tendency to form pills on theirsurface may be heated 5 superficially at certain critical temperaturesto eliminate or greatly decrease pill formation. It is necessary,however, to heat only the surface of the fabric and not the main body offibers. The present invention oflers a simple, economical, and highlyefiicient method for accomplishing this purpose.

It will be apparent that many widely different embodiments of thisinvention may be made without departing from the spirit and scopethereof, and therefore it is not intended to be limited except asindicated in the appended claims.

I claim:

1. A singeing apparatus comprising a hollow metal roll the lower portiononly of which is suspended in a heating chamber, a pair of frictionrolls located eutirely inside the heating chamber for rotating thehollow roll and both rolls being in contact with the said hollow rollthroughout its length, the said pair of rolls being mounted on bearingswhich are outside the said 6 heating chamber, means outside the heatingchamber for driving the said pair of rolls, heating means within theheating chamber along the sides thereof parallel to and facing the saidhollow metal roll, a narrow air gap separating the roll from the chambersides, and means for passing a fabric in wiping contact with the topsurface only of the said hollow roll.

2. The apparatus of claim 1 in which the hollow roll is heated by meansof a gas burning on the surface of the heating chamber walls.

References Cited in the file of this patent UNITED STATES PATENTS1,655,233 Machlet Ian. 3, 1928 1,664,993 Osthoif Apr. 3, 1928 FOREIGNPATENTS 21,995 Great Britain of 1903 314,597 Great Britain July 4, 1929

